| 中条山铜矿峪变质火山岩的时代、构造背景及对成矿的制约 |
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| 关键词:Zhongtiao Mountain Tongkuangyu Jiangxian Group Paleoproterozoic tectonic setting |
| 基金项目:中国地质调查局地质调查项目(编号: 12120114021501; 1212010811033);科技部基础性工作专项(编号: 2015FY310100);国家自然科学基金(编号: 41172171; 41203025);全国地层委员会项目(编号: 1212011120142) |
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| The Age and Tectonic Setting of Metavolcanic Rocks in the Tongkuangyu Deposit, Zhongtiao Mountain, and Their Constraints on Copper Mineralization |
| The formation time and tectonic setting of metavolcanic rocks of the Jiangxian Group in the Tongkuangyu copper ore district of the Zhongtiao Mountain remain controversial. SHRIMP zircon U-Pb dating reveals that the formation ages of the metamorphic quartz porphyry and metamorphic acidic volcanic rocks are (2179±7) Ma and (2142±11) Ma, respectively. The authors redivided the sequence of the metavolcanic rocks of the Jiangxian Group, in ascending order, into metamorphic quartz porphyrys (the Luotuofeng Formation), metamorphic mafic volcanics (the Xijinggou Formation) and metamorphic acidic volcanic rocks (the Shujinggou Formation). With post-collision granite features, the metamorphic quartz porphyry was formed in a tectonic setting from compression to extension between 2.18 Ga and 2.14 Ga. Nd isotopic analyses show that εNd(t) values of the metamorphic quartz porphyry range from –2.21 to –2.15, and the corresponding two stage model ages TDM2 are mainly between 2.75 Ga and 2.79 Ga. The metamorphic acidic volcanic rocks are of A2 type granite features, with εNd(t) values being –1.59 ~ –0.94, and two stage model ages being mainly between 2.63 Ga and 2.69 Ga. It is inferred that their magmatic origin was related to partial melting of older continental crust. The metamorphic mafic volcanic rocks are enriched in LREE, LIL and HFS elements, with Nb, Ta negative anomalies but no significant negative Ti anomalies. Some samples show Zr, Hf positive anomalies. These features are consistent with geochemical features of continental basalt, with assimilation of crust materials to various degrees in an extension tectonic setting. Zhongtiao–Lüliang Mountains might be located on the margin of the North China ancient continental block and underwent complicated geological evolution from orogeny to post-orogenic extension in the Paleoproterozoic period. The Tongkuangyu porphyry copper deposit was formed on the margin of the land mass in the conversional stage from compression to extension. |
| YANG Chong-hui,DU Li-lin,REN Liu-dong,SONG Hui-xia,GENG Yuan-sheng,WANG Yan-bin,LU Zeng-long,WANG Hao,LI You-he.2015.The Age and Tectonic Setting of Metavolcanic Rocks in the Tongkuangyu Deposit, Zhongtiao Mountain, and Their Constraints on Copper Mineralization[J].Acta Geoscientica Sinica,36(5):613-633. |
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